In such machines and methods, successive preforms are placed in successive molds and the injection is performed at a container forming wheel, or carousel, movable in rotation and carrying the molds. The injection is performed in a forming area of the wheel at a high pressure via injection means coupled to the molds. The forming station is defined as being an active forming station when the injection means are placed in fluidic communication with the inner volume of the preforms. By active, it is meant that the forming station is performing one of the steps of the forming and filling process.
The wheel comprises a loading area where the preforms are loaded in the molds and an exit area where the formed and filled containers are retrieved from the molds, the forming area extending between the loading area and the exit area.
Consequently, the forming wheel has to have a very large diameter to be able to comprise a loading area, a forming area and an exit area, while the forming area is reduced to a relative small part of the periphery of the wheel. This means that only a small number of the forming stations can be active at the same time. Indeed, a part of the periphery of the wheel has to be used to closed the mold and to place the injection means in fluidic communication with the inner volume of the preforms downstream of the loading area and another part of the periphery of the wheel has to be used to retract the injection means and open the mold upstream of the exit area.
Furthermore, at the exit area of a forming wheel, the formed and filled containers are subjected to a centrifugal force while they are opened, which can lead to a deformation or a destruction of the containers.
More particularly, when the formed and filled containers move from the forming wheel to the transfer wheel, the direction of rotation of the containers changes, which implies that the centrifugal forces applied by the forming wheel and the centrifugal forces applied by the transferring wheel are of opposite signs, which generates very important constraints on the formed containers. Such constraints applied by the liquid on the containers while they move at high speed can lead to a deformation or even a destruction of some of the containers, thereby spilling the content of these containers in the machine. There is therefore a high risk of soiling the machine with liquid, which requires stopping the machine to clean it and reduces the throughput of the machine.
Document WO-2012/156014 discloses such a machine for forming and filling containers, wherein the opened and filled containers are separated from injection nozzles while the molds are placed in a retracted position away from the injection nozzles. Such a machine has a reduced forming area as described previously, since a part of the periphery of the wheel has to be used to closed the mold and to place the injection means in fluidic communication with the inner volume of the preforms downstream of the loading area and another part of the periphery of the wheel has to be used to retract the injection means and open the mold upstream of the exit area. The machine is arranges such that, if liquid is spilled out of the containers, said liquid will not soil the molds, which reduces the need to clean the machine. However, such a machine does not prevent the spilling of the content of the containers. Such a machine is therefore not satisfactory since a part of the liquid injected in the containers is lost. Consequently, in order to prevent any spilling, the speed of rotation of the different wheels of the machine is necessarily limited, thereby limiting the throughput of the machine. To avoid excessive reducing of the machine throughput, one can imagine increasing the number of forming station around the forming wheel. A drawback of this solution is the higher cost of the machine.
One of the aims of the invention is to overcome the drawbacks mentioned above, by proposing a machine and a method for forming and filling containers, to allow addressing issues of a particular step of the container manufacturing process without excessively increasing the machine cost. An example of the issue that could be addressed may be the spilling of the liquid contained into the filled container.